1. Field of the Invention
The present invention relates to a laminate obtained by laminating a film made of a liquid crystal polyester resin composition and a metallic foil, having excellent molding processability, heat resistance and flexibility, and excellent adhesion between layers.
Further, the present invention relates to a laminate comprising a layer made of a liquid crystal polyester resin composition and a layer made of a fiber material, and a laminate comprising a metallic foil, a layer made of a liquid crystal polyester resin composition and a layer made of a fiber material, and relates to a laminate which has excellent heat resistance, and low relative dielectric constant, dielectric loss tangent and water absorption, and additionally which is cheap, used for electric and electronic parts, circuit and multi-layered substrates, and the like.
2. Description of the Related Art
Recently, with commercial requirements for light-weight electric and electronic parts and low cost parts, demand is drastically increasing for a flexible printed-wiring board composed of a laminated material made of a resin film, a metallic foil, and a film carrier tape. Therefore, laminated materials made of a thermosetting resin film such as an epoxy resin and a metallic foil have been developed, however, they have problems of poor productivity and high expense.
Furthermore, a laminate comprising a glass fiber textile impregnated with an epoxy resin, a polyimide resin layer and a metallic foil, is widely used in the industry as a multi-layered substrate, however, since the dielectric constant of the substrate is high and production process thereof is complicated, it is very expensive.
As the laminated material composed of a thermoplastic resin film and a metallic foil, Japanese Patent KOKOKU Publication (JP-B) No. 59-46786 discloses a method for obtaining a printed-wiring board by press-bonding a polyethyleneterephthalate (hereinafter, sometimes referred to as PET) film with a metallic foil. However, thus obtained printed-wiring board has insufficient heat resistance since PET has low heat resistance.
Japanese Patent KOKAI publication (JP-A) No.61-130041 describes a method for obtaining a laminated material for a printed-wiring board by molding of a liquid polymer film and a metal film using a press machine, and JP-A-2-252738, U.S. Pat. No. 496,807, JP-A-3-183185, JP-A-5-042603 and the like describe a method for obtaining a liquid polymer film for a printed-wiring board, or a method for obtaining a printed-wiring board laminate by press-bonding of a liquid crystal polymer film with a metal film with heating, and the like. Further, JP-B-8-2611 describes a laminate in which a liquid crystal polyester layer exists between metal plates, U.S. Pat. No. 5,360,647 and JP-A-4-53739 and the like disclose a laminated composed of a metal sheet and a liquid crystal polyester. However, the printed-wiring board using a liquid crystal polymer has various problems in that it is difficult to process a liquid crystal polymer into a film by a general method. Since it has poor film-forming processability, film deformation occurs since it has high anisotropy, and a flexible printed-wiring board can not be obtained since the liquid crystal polymer film has high stiffness, and the like.
JP-A-8-323923 describes a laminated material composed of a metallic foil and a film of a liquid crystal polyester resin composition comprising a liquid crystal polyester and a specific thermoplastic resin. However, it has problems that the appearance of the films is poor and adhesion between layers is insufficient.
Regarding a laminate using fiber material, for example, JP-A-62-11289 discloses a technique using an Aramid fiber instead of a glass fiber, however, in this case, there are problems that the Aramid fiber has high dielectric constant, and has water absorbing property. U.S. Pat. No. 4,975,312 discloses a multi-layered substrate using a biaxially-oriented liquid crystal polymer film, glass fiber and epoxy reinforcing material, however, the liquid crystal polymer film can not be formed as a thin film, and has insufficient physical properties. JP-A-2-175731 discloses a method in which an epoxy resin having low relative dielectric constant is impregnated into glass fiber, and the resulting resin material is used in a multi-layered substrate where, however, the effect is not sufficient. JP-A-62-283694, JP-A-8-157621 and the like disclose a method in which a porous sheet made of Teflon is impregnated with a thermosetting resin and the resulting sheet material is used as a prepreg. However, it is very expensive or has insufficient physical properties. Therefore, a laminate which has excellent heat resistance, and low relative dielectric constant, dielectric loss constant and water absorption, and which is also cheap has eagerly been commercially desired.